Topics - zutopian

Estimating the distribution of Galaxy Morphologies on a continuous space

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The incredible variety of galaxy shapes cannot be summarized by human defined discrete classes of shapes without causing a possibly large loss of information. Dictionary learning and sparse coding allow us to reduce the high dimensional space of shapes into a manageable low dimensional continuous vector space. Statistical inference can be done in the reduced space via probability distribution estimation and manifold estimation.

We present a catalog and imaging atlas of classical (collisional) RING galaxies distilled from the Arp-Madore Atlas of Southern Peculiar Galaxies and Associations and supplemented with other known RING galaxies from the published literature. The catalog lists the original host object, compiles available redshifts and presents newly determined positions for the central (target) galaxy and its nearest companion(s). 127 collisional RING systems are illustrated and their components identified. All of the RINGS have plausible colliders identified; many are radial-velocity confirmed companions. Finally, we make note of the existence of a rare sub-class of RING galaxies exemplified by AM 2136-492, double/concentric RING galaxies. These objects are predicted by numerical simulations, but they appear to be quite rare and/or short-lived in nature.

As a first step in the systematic study of large spirals, which may be useful in cosmological tests and studies of galaxy evolution, a catalog of the 107 largest known spiral galaxies is presented. Catalog galaxies have isophotal diameters greater than 90 kpc, assuming an H(zero) value of 50 km/sec per Mpc. UBVR photoelectric photometry is presented for 20 of these galaxies, and absolute magnitudes are derived for all galaxies in the catalog by transforming Zwicky magnitudes to the B(T) system.

The dataset included galaxies imaged by SDSS [6], and classified as spiral galaxies by Galaxy Zoo [7]. Then, the galaxies were analyzed using the Ganalyzer method [8,9], and were separated as described in [10] to 64,399 spiral galaxies that spin clockwise and 63,215 spiral galaxies that spin counterclockwise.

Here is a new paper by non-GZ astronomers, who checked some GZ classifications by using an automated galaxy morphology analysis method.:

Quantitative analysis of spirality in elliptical galaxies

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The results suggest that more than a third of the galaxies that were classified manually by Galaxy Zoo participants as elliptical actually have a certain spirality. Although in most cases the spirality was low, 10% of the galaxies classified as elliptical had a slope greater than 0.5, ...

I split this topic because it veers off from the subject of the workshop - Alice.

Concerning using our clicks:I think, that it is related to the "Zooniverse User Agreement and Privacy Policy", which was recently updated. There is a blog post from 24 Aug 2012.: http://blog.zooniverse.org/2012/08/24/updated-privacy-policy/I don't know the old Privacy Policy concerning the SN Zoo.I think, that it should also be discussed about Privacy Policy at the workshop.:There is given a somehow strange statement.:

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Therefore, if you contribute to the Zooniverse, you grant the CSA and its collaborators, permission to use your contributions however we like to further this goal, trusting us to do the right thing with your data.

When asked "Is there something odd?", there is the Option "Other". I wonder, what "Other" can stand for? For what reasons do classifiers click "Other"? How often did we click "Other"?Does the GZ Team follow up the "Other" clicks? If so how? ( "Other" can mean anything.)Does it make sense to click the "Other" option? Or is it just a waste to click "Other"?

We report the discovery of Seyfert-2 galaxies in SDSS-DR8 with galaxy-wide, ultra-luminous narrow-line regions (NLRs) at redshifts z=0.2-0.6. With a space density of 4.4 per cubic Gpc at z~0.3, these "Green Beans" (GBs) are amongst the rarest objects in the Universe. We are witnessing an exceptional and/or short-lived phenomenon in the life cycle of AGN. The main focus of this paper is on a detailed analysis of the GB prototype galaxy J2240-0927 (z=0.326). Its NLR extends over 26x44 kpc and is surrounded by an extended narrow-line region (ENLR). With a total [OIII]5008 luminosity of (5.7+/-0.9)x10e43 erg/s, this is one of the most luminous NLR known around any type-2 galaxy. Using VLT/XSHOOTER we show that the NLR is powered by an AGN, and we derive resolved extinction, density and ionization maps. Gas kinematics is disturbed on a global scale, and high velocity outflows are absent or faint. This NLR is unlike any other NLR or extended emission line region (EELR) known. Spectroscopy with Gemini/GMOS reveals extended, high luminosity [OIII] emission also in other GBs. WISE 24micron luminosities are 5-50 times lower than predicted by the [OIII] fluxes, suggesting that the NLRs reflect earlier, very active quasar states that have strongly subsided in less than a galaxies' light crossing time. These light echos are about 100 times more luminous than any other such light echo known to date. X-ray data are needed for photo-ionization modeling and to verify the light echos.